1. Field
The described technology generally relates to an electrostatic chuck for manufacturing a flat panel display such as an organic light emitting diode (OLED) display.
2. Description of the Related Technology
An OLED is a self-emitting display device using a phenomenon, in which electrons and holes injected through the positive pole and the negative pole are recombined in an organic layer formed with a monomer, a low molecule, or a polymer to form an exciton, so that light in a particular wavelength is generated by energy from the formed exciton.
The positive pole of the OLED may employ an indium tin oxide (ITO) film having a low sheet resistance and a good permeability, and the organic layer may employ a multilayer structure of a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electronic transport layer (En), and an electronic injection layer (EIL) in order to improve the light emitting efficiency. Further, the negative pole may employ a metal film of LiF—Al, etc.
A manufacturing process of the OLED is generally divided into three steps of a pre-process, a post-process, and an encapsulation process. The pre-process, which is a process of forming the ITO thin film on a crystal substrate by using the sputtering, has been already commercially available for manufacturing a liquid crystal display. The encapsulation process is a process of sealing a device for extending the durability of the device because the organic layer is very weak against moisture and oxygen in the air. The post-process is a process of forming an organic layer and a metal layer on a substrate. The post-process mainly employs a vacuum deposition method which evaporates an organic material in a high vacuum atmosphere and forms a pixel patterning by using a shadow mask on a substrate.
In an active drive-type OLED display device among the OLED display devices, the pixels, which are the basic units for an image representation, are arrayed in a matrix form. Further, a thin film transistor (TFT), serving as a switching device, is disposed for each pixel, to independently control the pixel.